Comparison of the Methods for the Determination of Surface Acidity of Solid Catalysts

Abstract

Abstract The concept of surface acidity was originally introduced with the aim of justifying the presence of some substances formed in catalytic chemical reactions, not as a consequence of suppositions about the nature of surface-active sites of solid catalysts. The formation of such substances in some reactions (e.g., cracking, isomerization, or polymerization) can be better explained by admitting the formation of reaction intermediates having the structure of a carbonium ion, which can be formed by interaction between the reacting substance (hydrocarbon) and an acid center. As an example, in the cracking of alkylaromatics catalyzed by decationated zeolites, the following reaction mechanism is generally accepted: